Electric telegraph equipment



June 30, 1959 H. D. GAITE ELECTRIC TELEGRAPH EQUIPMENT 4 Sheets-Sheet 2 Filed May 25, 1955 .fixoom mucoo Pmwh huxoom om om ux F CCC (C c c UPISM 3 mun-i, :otiw

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mo E 026 Q m6 United States Patent '0 7 ELECTRIC TELEGRAPH EQUIPMENT Harold D. Gaite, Taplow, England, assignor to British Telecommunications Research Limited, Taplow, Eng- 1 land, a British company Application ,Ma'y as, 1955, Serial No. 511,066 Claims priority, application Great Britain June -4, 1954 9 claims. v(c1. 17 8-2) The present invention relates to "electric telegraph equipment and is more particularly concerned with the provision of a control unit suitable for controlling the operation of a plurality of tape readers and/or coders together with automatic message numbering equipment. Tape readers are well known in the art and generally comprise equipment for driving punched tape step-byst'ep together with a set of five peckers which sense the' holes 'inthe tape and operate contacts when holes are encountered. The expression coder is intended to cover a unit by means of which a series of signals of a predetermined but adjustable nature can be transmitted over the line and this may conveniently take the form of a switching device employing a plurality of balls selectively "out automatically, including the changeover from one tape reader to another, the automatic insertion of the message number and the provision of the "call sign. Facilities are also provided whereby a test message or a routine message may be transmitted in response to the throwing of a test key or alternatively a keyboard may be connected up to enable a suitable. message to be keyed. According to the invention the various operations are conveniently controlled by an electromagnetically-operand 'step-by-step switch, for instanee of the type commonly known as a uniselector, which is stepped suitably under'the control of a group of relays and over its'var ious wipers enables the desired switching operations to be carried out.

- The invention will be more fully understood from the following description of a preferred form which should be taken in conjunction with the accompanying drawings comprising Figs. 1-6. Of these Fig. 1 shows a known type of uniselector in suflicient detail to permit its method of operation to be appreciated, Fig. 2 shows the assumed grouping of the pins on its base by which it is plugged into a suitable socket and Fig. 3 indicates the manner in which its banks would be wired to these pins and the significance of the different contact positions. Fig. 4 shows the interconnection between the banks A-E of the uniselector, that is to say, those banks over which the actual control of the signals is efiected and also indicates the various bases or sockets into which the tape readers coders and keyboard would beplugged. Figs. 5 and- 6 when fitted together with Fig. 5 on the left, represent a circuit diagram showing how the connections to the control bank F of the'uniselector serve to produce the desired operation in'connection "with the other units and the group of control relays. It should be mentioned 'in the comparatively simple circuits here involved.

that in Fig. 4 the connections from the various sockets which terminate in arrow heads extend to the corresponding points on Figs. 5 and 6 where they are marked with a similar notation. Thus in Figs. 5 and 6, certain pieces of equipment attached to the diiferent plugs have been show in order to facilitate the understanding of the circuits, for instance the magnet N on the extreme left of Fig. 5. Such pieces of equipment are shown as connected up over plug and socket points which are numbered to correspond with the socket numbering in Fig. 4.

Considering first Fig. 1, this shows a known construction of uniselector which is operated by an electromagnet 13 provided with an armature 14 carrying a pawl 15 engaging with a ratchet wheel 16. The switch is provided with 12 positions and the wipers which engage with the various bank contacts each comprise a spider with three equally-spaced arms such as 17 and the bank contacts 18 occupy of arc. A further position W serves to permit the necessary connections to be made to the Wipers by a slip ring arrangement as is well understood. Stepping or the wipers takes place on energisation of the electro'magnet and in the form shown the switch is assumed to have six banks or levels A-F. The table of Fig. 3 indicates the wiring of the bank contacts to the contacts in the base on which the switch is mounted as shown in Fig. 2 and the significance of the wiring arrangements will be appreciated as the description proceeds.

In the showing of the switch in Fig. 4, the bank contacts are indicated as black dots and the well known convention has been adopted of showing the interconnections by a single line representing a multiple cable. This method of presentation can be followed without difiiculty It will be seen also that in order to avoid complicating't he drawing, the showing'of'Fig. 4 does not include the control bank F of the uniselector and this is dealt with in Fig. 5 in which the banks A-E do not appear. It should be mentioned also that the base 'SKV in which is inserted the plug PLV from the feed wipers of the uniselector extends to a distributor, for instance of the electronic type as described in detail in my application Seiial No. 502,584, filed April 20, 1955, whereby the potentials selectively applied simultaneously to the signalling leads are given the appropriate time sequence.

Considering now thecircu'it diagram of Figs. 5 and 6, this includes a number of electromagnets which are used for stepping the various pieces of equipment such as coders andtape readers which may be associated with the control unit. The magnet N serves to step the coder which controls the transmission of the serial nui'nberof the message, this stepping operation taking place at the end of the message in order to add one unit to the number. Magnet Y serves to step the Y tape reader, magnet Z steps the Z tape reader, magnet T steps the test coder by means of which a test message can be repeatedly transmitted for as long as is desired, magnet Q steps the routine coder, magnet U steps the uniselector and magnet P steps the preamble coder for generating the call sign and efie'cting the proper setting of the receiving equipment to receive the message.

As regards the operation of the distributor, it should be explained that this is set in operation by the connection of earth to terminal V7, Fig. 6, and this applies pulses to terminal V12 at the appropriate transmission speed. The connection of earth to terminal V11, Fig. 5, results in the transmission of a continuous mark signal and similarly the connection of positive from terminal V10 to terminal V9. Fig. 6 ensures the transmission of a'continuous space signal.

Considering now the operation of transmitting messages under the control of tapes in the Y and Z tape readers plugged into the double sockets SKYA and SKYB a. 3 and SKZA and SKZB respectively, it will be assumed that the equipment is in the position shown with the uniselector in its home position which is position 2. In these circumstances a small current flows through magnet N which is not enough to cause its operation but prevents the capacitors C1, C2 and C3 from being charged to any appreciable extent. Moreover as may be seen from Fig. 4, in this position earth is connected to the contacts in banks A-E and this earth is extended to the distributor to produce a letter shift signal.

Assuming that a tape has now been properly placed in the Y tape reader, the tape sensing contacts TSY, Fig. 5, will be closed and a circuit will then be completed from earth over contacts F1 and TSY, relay A, resistor R8 and relay F to positive. Relay F is somewhat slow to operate owing to the large value capacitor C7 shunting its winding but relay A operates immediately and at contacts A1 prepares a circuit for relay E, at contacts A2 completes a locking circuit for itself independent of contacts F1, at contacts A3, Fig. 6, removes the short-circuit from the tight tape contacts TTY so as to render these contacts effective, and at contacts A4 prepares a stepping circuit for magnet Y of the Y tape reader. Relay F on operating after its slow period, at contacts F1 opens the initial circuit for relay A, at contacts F2 opens a point in the energising circuit for relay B,'at contacts F3 opens a point in the energising circuit for relay J and at contacts F4 extends earth over contacts G3, switch SWD2, contacts B3 and TTY to terminal V7. The distributor is accordingly set in operation and a driving pulse is shortly applied to terminal V12 whence it is extended over contacts E3 and H1 to operate magnet U and cause the uniselector to step to position 3. Wiper F now opens the circuit of magnet N and permitsrcapacitors C1, C2 and C3 to start to charge. As shown in Fig. 4, bank contacts A-E in position 3 are wired in the same way as those in position 2 so that the equivalent of a letter shift signal is again transmitted. The distributor continues to operate and the next pulse over terminal V12 steps the uniselector to position 4. Here again banks A-E are connected to earth but over bank F earth is connected to terminal V11 to ensure the transmission of a continuous mark signal and the uniselector then steps to position 5. The wiring in this position is similar and consequently a mark signal is again transmitted.

The next pulse from the distributor advances the uniselector to position 6 in which banks A-E are wired for the preamble coder by way of socket SKP as shown in Fig. 4. This initial period of 450 milliseconds without signalling allows the motor of the receiver to approach its normal running speed from the position of rest and thus to be in synchronism with the transmitter.

In position 6 of the uniselector a circuit is completedover the F wiper, Fig. 5, and contacts PA for relay H which accordingly operates and at contacts H1 connects up magnet P in place of magnet U so that at the end of the first character when the driving pulse is received from the distributor, magnet P of the preamble coder is operated. The various characters of the call sign are thus transmitted in turn, the coder being advanced one step after each character and during the transmission of the last character, during which a figure shift is transmitted, the switching member PA is changed over mechanically so as to release relay H and prepare an alternative circuit for it. Relay H therefore again connects up magnet U which is operated by the next drive pulse from the distributor to advance the uniselector to position 7.

Positions 7, 8 and 9 of banks A-E are wired.to the peckers of the serial number coder connected to socket SKN, Fig. 4, which therefore controls the transmission of the three digits of the serial number, the uniselector being advanced one step after each digit. When it arrives in position 10, a circuit is again completed for' relay H which therefore again connects up the magnet P of the preamble coder. It will be seen from Fig. 4 that positions 6 and 10 of banks A-E are wired together. The preamble coder is therefore operated further and now serves to transmit carriage release, letter feed and line space signals to effect the correct positioning of the platen or printing head of the receiving printer in preparation for the message proper. -When this transmission is completed, contacts PA are restored to their original position as shown in Fig. 5 and relay H therefore releases and again connects up the magnet U of the uniselector. This is operated by the next drive pulse from the distributor to advance the uniselector to position 11.

In this position a circuit is completed over bank F and contacts A1 for relay E which accordingly operates and at contacts E1, Fig 6, opens a point in the holding circuit for relays D and G, at contacts E2 removes one of the connections for applying earth to the distributor hold lead over terminal V7 and at contacts E3 connects up the magnet Y of the Y tape reader. The peckers of this reader are now effective over banks A-E, position 11, and the transmission of the message on the tape therein now takes place. The tape is advanced one step after each character by magnet Y which is energised by successive pulses from the distributor applied to terminal V12.

At the end of the transmission when the tape has run out, the tape sensing contacts T SY are opened and interrupt the circuit of relays A and F. Relay A thereupon releases but before relay F has released, a further circuit is completed forit over wiper F in position 11, back contacts A1, rectifier MR1 and resistor R7. Relay E is released by the opening of contacts A1 and thereupon at contacts E3 transfers the pulse circuit back to magnet U. Accordingly when the next pulse is received the uni selector is advanced to position 12.

In this position a similar circuit is completed for relay F over back contacts B1 and the connections therefore remain the same and the uniselector is advanced to position 1. In this position relay F is maintained over back contacts J1 and hence the uniselector is advanced to position 2. In this position there is no longer any circuit for relay F and it releases, thereby at contacts F4 removing earth from the distributor hold lead and thus arresting its operation. Moreover capacitors C1, C2 and C3 are now able to discharge through magnet N which therefore steps the serial number coder so as to add one unit to constitute the number next to be transmitted. The equipment has therefore now been restored to normal and unless there is a tape in reader Z or the test message or routine coders are brought into operation, no further action will take place.

If however there is already a tape in the Z tape reader, contacts TSZ will be closed and on the closure of contacts F2 when relay F releases, a circuit is completed from earth over contacts J2, A2, TSZ and F2 for relays B and F in series. Relay B operates immediately and produces effects in all respects similar to those produced by relay A but in relation to the Z tape reader so that transmission takes place under the control of this reader in the manner just described. While the message represented by the tape in the Z reader is being transmitted the Y tape reader can be provided with a further length of punched tape. Similarly the Z reader may be recharged while sending takes place under the control of the. Y reader and on this basis sending may take place continuously as long as the traffic persists.

' If it is desired to transmit a message without a serial number, key SWA is operated and this by closing contacts SWAI maintains a circuit through magnet N and prevents the charging of capacitors C1, C2 and C3 and thus the subsequent stepping of the serial number coder.

Moreover these contacts remove the short-circuit from the gas discharge tube LPI and this strikes to furnish a visual indication-that the numbering operation has been the magnet T of the test coder.

SWB. .erally similar to that of relays A and B except that in this uniselector and hence that the output is held at mark during this period. This method of operation may be desirable if for some reason the tape has been wrongly inserted and needs to be removed for readjustment.

If it is desired to transmit a test message, which would ordinarilybe done at a time when there was no tape in either of the tape readers, the key SWB is operated. This thereupon completes a circuit from earth over contacts G1, D1 and F3 for relay J in series with relay F. Relay J on operating, at contacts 11 prepares a circuit for relay E, at contacts J2 opens-the initial circuit for relays A and B, at contacts 13 completes a' locking circuit for itself and at contacts/J4 prepares a circuit for Relay F operates as before after a short delay and by applying earth to terminal V7 starts theoperation'of the distributor and hence the stepping of the uniselector. Relay F also at contacts F3 completes a holding circuit for relay J to ensure a complete cycle ofthe uniselector independently of switch It will be seen that the effect of relay J is gencase the uniselector comes to rest in position 1 and the test message is sent out under the control of the test coderplugged into socket SKT, Fig. 4.

When it is desired to stop sending the test message .whichwill otherwise continue indefinitely, switch SWB isrestored and the message is then completed under the control of off normal contacts TA, Fig. 3, on the test coder, which restore to the position shown when the message is completed. This releases relay J andhence relay -E and permits the uniselector to step to its normal position 2; Relay F is then released and by removing earth from the distributor hold lead, terminates the operation of this equipment. a V V If'operation is to take place under the control of the routine coder, which serves for the sending of short mess'a'ges which are frequently used, switch SWC is momentarily operated and a circuit is then completed from earth by way of contacts 63, switch SWD2, contacts B3, A3, F g-SWC, relay D, contacts F3, relay J, resistor-R11, relay F to positive. Relays D and-J both operate in this circuit and relay J produces substantially the same'efiects as before. Relay D at contacts D1 disconnects switches SWB a'nd SWF, at contacts D2 completes a lockingcircuit for itself, at contacts D3 opens a point in the initial circ'uit'for relay G and at contacts D4 connects up the magnet Q of the'routine coder. As before the uniselector steps round to position 1 and transmission is now controlled by the routine coder. Contacts QA are operated as seen "as this coder which is'plu ged intosocket SKQ,.

Fig. 4 steps from its normal position and serve to maint'aimthecircuit of relay D after it is opened at contacts E1. When the routine message has been transmitted,

contacts QA are again opened and relays D, -J-, E and F are released and the unisele tor is stepped on to posia tion 2.

If it is desired to stop a transmission which is in progress from either of the tape readers, key SWD is operated. This thereupon at contacts SWD2, Fig. 6, removes the earth froiri' the distributor hold lead-by Way of terminal V7 and this arrests the operation of the distributor.

Moreover switch SWD Z in its alternative position completes a locking circuit for relay B if this relay is the one that has been operated, while if on the other hand r elay Ahas been operated corresponding to tape reader Y-, a locking circuit forthis relay is completed'over concall sign and message number-(to be transmitted when a message is sent from a common transmitter to several channels at once. It will be seen thatswitch SWF produces the same effect as switch SWB except that its operation is only momentary. Relay J is operated as before and is locked up dependent on contacts E-l. Hence no message is sent when the uniselector steps round to position 1 since relay E operates momentarily and releases relay J and the result is the transmision of the call sign and message number only.

If the keyboard is to be brought into use, the switch MA, Fig. 6, is operated and a circuit is then completed from earth over contacts D3, switch MA, relay G, contacts F3, relay J, resistor R11, relay F to positive. The operation of relays F and I produce the same results as previously and relay G at contacts G1 opens the circuit for relay I over switch SWB, at contacts G2 completes a temporary locking circuit for itself to ensure a full cycle of the uniselector in case switch should be restored prematurely, at contacts G3 prepares a circuit for applying pulses to terminal V7 and-at contacts G4 connects up the key release magnet of the keyboard so that this will be operated from the distributor. This magnet is not shown in Fig. 6 but it will be connectedbetween points M5 and M14 when the keyboard is plugged into socket SKM, Fig. .4. It will be appreciated that for the call sign and serial number transmissions earth is provided over contacts E2 but this connection is removed when relay E operates on theiuniselectorreachingposition 1 and also relays F, I, and G are then solely depend cut onthe keyboard switch MA. 1

vIt should be explained that negative is normally-connected from the distributor througha-resistorto terminal V15, Fig. 6, and consequently capacitor CM is charged. The contacts MB are changed overfonie'achkey operation and the capacitor then; discharges-over contacts G3, switch SWDZ, contacts B3,,A3 and F4 to apply a negative pulse to terminal V7 for a-predetermined time. The values of the components are so chosen that this pulse has the effect of releasing the hold-circuit of the distributor for approximately 20 milliseconds only, the distributor then runningon to complete one character cycle. Further operation is then dependentupon receipt of the next pulse resulting from. a further ;key operation.

It will be seen that suitable interlocks are provided to prevent the possibility. of morethan one piece of equipment controlling transmission at the same time. There might be a tendency for this to happen for instance if the power was switched on at a time when one or both the tape readers had beenfproperly provided with perforated tape and switch SWB had beenthrown to send a test transmission. If both tape readers wererea'dy to send, a circuit would be completed initialllyfor both relay A and relay B butthe operation of contacts A2 would then open the circuit of relay B. so that-they tape reader would have priority. ,.If.-in addition sw itch SWB was thrown, relay J wouldgbe operated and at contacts J2 would open the locking circuits of both r'elay A and relay B. I Y 1 a Conflict might arise however between the routine coder and the test message coder and theikeyboard, the peckers of all of which are multipled-together as indicated in Fig. 4. It be noted however that if relay J is already operated owing to the operation of switch SWB, relays D and G are both short circuited so'that' no result is produced if either switch SW6 or switch MA is operated. If on the other hand relay D is already operated for the sending of a routine test message, switch SWB is disconnected at contacts D1 and switch MA at contacts D3. Similarly if relay G is energised and key SWC is operated, relay D cannot be energised as its circuit is open at contacts G3. Moreover key SWB is disconnected at contacts G1. These electrical interlocks ensure that the equipment will operate in the manner intended even in somewhat abnormal circumstances.

ing of the equipment.

Contacts T'I'Y and 'ITZ are the usual tight tape contacts which open and stop transmission if the tape should get into such a condition that it will not feed properly. The

opening of eitherof these contacts will remove earth from terminal V7 and thus arrest the operation of the distributor.

For each cycle of the uniselector the peckers connected to positions 11, 12 and 1 are examined in turn but the message comes from only one of these. Rectifier MR2 enables the output to be held at mark while the uni- 'selector wipers are examining tape reader peckers which are not in use, preventingthe transmission of an unwanted character if a waiting tape is in position. The pecker contacts associated with position 1 are all open at rest and if J1 were connected in the same way as A1 and B1 at the end of a coder or keyboard message the output would be pulled to mark halfway through a character when J1 releases. Therefore rectifier MR1 is used to isolate the mark hold circuit from J1 and an allblank character is sent when the uniselector wipers reach position 1. a

-=It will be appreciated that though in most cases there would be no advantage in employing more than two tape readers, this could if required readily be done by suitable extension of the-circuits shown in Figs. 5 and 6.

- I claim:

1. A control unit for a telegraph system comprising in combination, a'stepping switch provided with a plurality of wipers-and a plurality of sets ofbank contacts for cooperation therewith, electromagnetically-operated means :for advancing said wipers-step by step to engage said sets of contactsin turn, connections extending respectively from a plurality of said sets of contacts to a like plurality of sockets for the plugging-in of tape readers, connections extending respectively from other of said sets of contacts to sockets for the plugging in of equipment for controlling the transmission of special signals and control circuits for effecting the movement of said stepping switchthrough a complete cycle in respect of'the transmission of a message over any one of said tape reader sockets. Y

2. A control unit for a telegraph system comprising in combination, a stepping switch provided with a plurality of wipers and a plurality of sets of bank contacts for cooperation therewith, electromagnetically-operated means for advancing said wipers step by step to engage said sets of contacts in turn, connections extending respectively from a plurality of said sets of contacts to a like plurality of sockets for the plugging in of tape readers, connections extending respectively from other of said sets .ofcontacts to. sockets for the plugging in of coding equipment for controlling the'transmission of special signals and control circuits for effecting the movement of said stepping switch through a complete cycle in respect of the transmission of a message over any one of said coding equipmentsockets. r

, 3. A control unit vfor a telegraph system comprising in .combination, a stepping switch provided witha plurality of wipers and a plurality of sets of bank contacts for cooperation therewith, electromagnetically-operated means for advancing said wipers step by step to engage said sets .of contacts in turn, connections extending respectively spect of the transmission of a message over any one of said tape reader sockets and in respect of the transmission of a message over said keyboard socket.

4. A control unit for a telegraph system comprising in combination, a stepping switch provided with a plurality of wipers and a plurality of sets of bank contacts for cooperation therewith, electromagnetically-operated means for advancing said wipers step by step to engage said sets of contacts in turn, connections extending respectively from a plurality of said sets of contacts to a like plurality of sockets for the plugging in of tape readers, connections extending respectively from other of said sets of contacts to sockets for the plugging in of equipment for controlling the transmission of special signals for association with messages transmitted over any one of said tape reader sockets, and control circuits for effecting the movement of said stepping switch through a complete cycle in respect of the transmission of a message over any one of said tape reader'socketsJ 5. A control unit as claimed in claim 2 in which one of said pieces of coding equipment is a message number counter and the number set up thereon is advanced one unit for each cycle of said stepping switch.

6. A control unit as claimed in claim 5 in which a capacitor is charged at the beginning of the cycle of said stepping switch and discharged through the said message number counter atthe end of said cycle to elfect the advance of said counter.

7. A control unit as claimed in claim 1 in which said stepping switch occupies a home position when no transmission is taking place and said wipers are arranged to be advanced over a plurality of sets of contacts engaged thereby before they engage the sets of contacts to which are connected the equipment for controlling the transmission of special signals, thereby providing a delay period to enable receiving equipment to reach its proper speed.

8. A control unit as claimed in claim 2 in which a plurality of sockets for the connecting up of coding equipment for controlling the transmission of special signalsare associated with one of said sets of bank contacts and electrical interlocking arrangements are provided to ensure that if plugs are present simultaneously in said sockets, only one of said pieces of equipment shall be effective.

9. A control unit as claimed in claim 8 in which the piece of equipment to be used is rendered eifective by the operation of a manually-controlled switchassociated therewith but only if the similar switch associated with another piece of said equipment has not previously been operated.

References Cited in the file of this patent UNITED STATES PATENTS 2,116,506 Carr May 10, 1938 2,116,549 Zenner May 10, 1938 2,340,576 Bacon Feb. 1, 1944 2,451,045' Potts Oct. 12, 1948 2,613,265 Halvorsen Oct. 7, 1952 2,667,533 Zenner Ian. 26, 1954 

